I purposely booked a stateroom on the bottom deck toward the stern to be out of the way. I can also be in my stateroom about 10 seconds after boarding.
I also worried that they might upgrade me but found out it would be unlikely given my circumstances.
I booked outside because there was really little difference in price between outside and inside staterooms, at least that was the case on HAL.
I'm glad to know that not everyone looks on the bottom deck as where the peasants sleep.